Method and apparatus for measuring the density of a fluid

ABSTRACT

A fluid densitometer and its method of use, comprising directing a fluid jet into a fluid whose density is to be measured and towards an open end of a tube. The nozzle and tube have a turbulent jet forming space extending between them a distance of less than fifty times the maximum distance across the nozzle orifice, and the fluid pressure in the tube is measured to determine the density of the fluid into which the jet is directed. The geometry of the fluid jet is derived from

United States Patent [191 Tanney 1 METHOD AND APPARATUS FOR MEASURINGTHE DENSITY OF A FLUID [76] Inventor: John W. Tanney, 34 l-IarwickCrescent, Ottawa, Ontario, Canada 221 Filed: Mar. l3, 1973 211Appl.N0.:340,9 29

[52] U.S. Cl. 73/32 Primary Examiner-Richard C. Queisser- AssistantExaminer-Stephen A. Kreitman Attorney-James R. Hughes Jan. 8, 1974 [57]ABSTRACT A fluid densitometer and its method of use, comprisingdirecting a fluid jet into a fluid whose density is to be measured andtowards an open end of a tube. The nozzle and tube have a turbulent jetforming space extending between them a distance of less than fifty timesthe maximum distance across the nozzle orifice, and the fluid pressurein the tube is measured to determine the density of the fluid into whichthe jet is directed. The geometry of the fluid jet is derived from R hp)/# R is the Reynolds number and is in excess of 1700, V is thevelocity of the fluid delivered to the device, p is the density of thefluid delivered to the device, n is the viscosity of the fluid deliveredto the device,

and h is the hydraulic radius obtained from,

h=(4A)/(P where A is the area of the fluid jet orifice,'and P is thedistance around the perimeter of the fluid jet orifice.

8 Claims, 18 Drawing Figures JET f, Lj/f/ FLOIV AIR SUPPLY Il [1 l'illPATENTEB 3.783.676

swan 1 OF 6 AIR 5 SUPPLY PATENTEUJAN 81974 3783676 SHEET 3 BF 6 PATENTED81974 3.783.676

SHEET 5 0F 6 PowER SUPPLY I FLU l D [C REFERENCE DEN SITONETER UNITPRESSURE MEASURING INDICATING 0R RECORDING DEvICE FEGIE.

PowER SUPPLY PRESSURE RATIO OR PREssURE DIFFERENCE 4/ CONTROLLER FLUIDICREFERENCE DENSITOMETER UNlT PREssURE MEASURING INDICATING 0R RECORDINGDEVICE FIGIT.

PATENTED JAN 81974 SHEET 5 OF 6 .1 METHOD AND APPARATUS FOR MEASURINGTHE DENSITY OF A FLUID This invention relates to a method and apparatusfor measuring the density of a fluid.

Ideally a fluid densitometer should respond only to the density of thefluid to be measured, and should in other respects be substantiallyinsensitive to its environment. Ruggedness is a very important featurefor a fluid densitometer because the probability of damage duringinstallation and use is reduced.

' It is an object of the invention to provide a fluid densitometer whichis substantially insensitive to its environment, and which is rugged.

According to the present invention there is provided an apparatus formeasuring the density of a fluid substance, comprising,

b. a pressurized fluid source connected to the device to deliver a fluidthereto at substantially constant pressure and cause a turbulent jetoffluid to issue from the orifice into the fluid substance.

c. a receiver means including a receiver mouth facing the orifice to bepressurized by the dynamicpressure of the jet therefrom, and fluidsubstance entrained therein, within the area bounded by the receivermouth.

d. mounting means connecting the receiver means and the device with aturbulent jet forming space extending between them a distance of lessthan fifty times the maximum distance across theorifice,

e. indicating means connected to the receiver means for indicating, interms of the fluid pressure therein the density of the fluid substance,

f. and wherein the geometry of the fluid jet orifice is derived from, Y

R is the Reynolds number and is in excess of I700,

V is the velocity of the fluid deliveredto the device,

p is the density of the fluid delivered to the device,

t is the viscosity of the fluid delivered to the device,

and

h is the hydraulic radius obtained from, h=(4A)/P, where A is the areaof the fluid jet orifice, and

P is the distance around the perimeter of the fluid jet orifice.

Further according to the present invention there is provided a method ofmeasuring the density of a fluid substance comprising,-

, a. mounting a nozzle device and a receiver means in the fluidsubstance with a receiver mount of the receiver means facing an orificeof the device for the receiver mouth to be pressurized by the dynamicpressure of a jet therefrom and with a turbulent jet forming spaceextending between the orifice and the receiver mouth of less than fiftytimes the maximum distance across the orifice,

b. delivering a fluid at substantially constant pressure to the deviceto cause a turbulent jet to issue from the orifice into the fluidsubstance and pressurize the receiver means by means of the dynamicpressure in' the turbulent jet and fluid substance entrained therein,and

c. determining, in terms of the fluid pressure within the receiver, thedensity of the fluid substance,

d. and wherein the geometry of the fluid jet orifice is derived from R(V h p)/;.:., where R is the Reynolds number and is in excess of 1700,

V is the velocity of the fluid delivered to the second device,

p is the density of the fluid delivered to the second device,

p. is the viscosity of the fluid delivered to the device,

and

h is the hydraulic radius obtained from, h=(4A)/P A is the area of thefluid jet orifice, and

P is the distance around the perimeter of the fluid jet orifice of thesecond device.

In the accompanying drawings which illustrate, by way of example,embodiments of the invention,

FIG. 1 is a diagrammatic sectional side view of an apparatus formeasuring the density of a fluid substance,

FIG. 2 is a graph of the fluid pressure in the receiver mouth, of theapparatus shown in FIG. 1, plotted against the density of thesurrounding fluid, with the nozzle and receiver spaced at five times thenozzle orifice diameter, V

FIG. 3 is a graph of the fluid pressure in the receiver mouth of theapparatus shown in FIG. 1, plotted against the density of thesurrounding fluid, with the nozzle and receiver spaced at variousdistances,

FIG. 4 is a sectional side view of the nozzle and tube shown in FIG. 1,adapted to measure the density of a stream of a fluid substance,

FIG. 5, is a sectional end view along VV, FIG. 4,

FIG. 6 is a similar sectional end view to that shown in FIG. 5, but of adifferent apparatus,

7 FIG. 7 is a similar view to that shown in FIG. 4 but of anotherdifferent apparatus,

FIG. 8 is a similar view to that shown in FIG. 4 but of a furtherdifferent apparatus,

. FIG. 9 is asimilar view to that shown in FIG. 4 but of anotherdifferent apparatus,

FIG. 10 is a similar view to that shown in FIG. 4 but of a furtherdifferent apparatus,

FIG. 11 is a plan view of an apparatus, for measuring the density of afluid, mounted in a wall member,

FIG. 12 is a side view of the apparatus shown in FIG. 11,

FIG. 13 is a sectional side view of a fluid jet forming device and areceivermeans, both mounted in a casing, and for use as a comparatorwith the apparatus described with reference to FIGS. 1 through 10,

FIG. 14 is a similar view to FIG. 13, but of a different comparator,

FIG. 15 is another similar view to FIG. 13, but of another comparator,

FIG. 16 is a flow diagram of the apparatus shown in any of FIGS. 13through 15 coupled to the apparatus shown and described with referenceto any of FIGS. 1 through 10,

FIG. 17 is a different flow diagram to that shown in FIG. 14, and

FIG. 18 is a an adjustable apparatus for measuring the density of afluid substance.

In FIG. 1 there is shown a fluid jet forming device, in theform of anozzle 1, having a fluid jet orifice, a pressurized fluid source, in theform of an air supply 3, connected to the nozzle 1 to deliver a fluidthereto at substantially constant pressure and cause a turbulent jet offluid to issue from the orifice into the fluid substance. A receivermeans inthe form of a tube 2, includes a receiver mouth facing theorifice to be pressurized by the dynamic pressure of the jet therefrom,and fluid substance entrained therein, within the area bounded by thereceiver mouth. The tube 2 and nozzle 1 are mounted with a turbulent jetforming space extending between them a distance of less than fifty timesthe maximum distance across the orifice. Indicating means, in the formof a manometer 4, is connected to the tube 2 for indicating in terms ofthe fluid pressure therein the density of the fluid substance.

The geometry of the fluid jet orifice is defined as its hydraulic radiush being such as to produce a turbulent jet on the basis of the velocityV of the supply fluid from the pressurized fluid source at the outlet ofsaid orifice, the density p of such supply fluid, the viscosity p. ofsuch supply fluid, and the hydraulic radius h combining, with consistentdimensions to produce a dimensionless Reynolds number R is excess of1700 from the relationship where the hydraulic radius h is defined interms of the area A of the fluid jet orifice in the place of the outletof said orifice and the perimeter P of said orifice in said plane by therelationship h=(4A)/P The velocity V of said supply fluid at the outletof said orifice may be determined experimentally or derived by thoseskilled in the art from published texts.

In this specification "turbulent jet forming space is defined as a spacein which the turbulent jet is allowed to expand in a manner similar tothe expansion ofa turbulent jet in a volume which is unbounded at leastto one side.

In operation the apparatus is arranged as shown in FIG. I, with thenozzle 1 and receiver 2 mounted in the fluid substance whose density isto be measured, in this instance a gas. The apparatus was arranged withthe distance x five times the minimum distance across the fluid jetorifice of the nozzle 1, which in this case was the diameter d". Aturbulent jet of air was directed from the nozzle towards the tube 2.

The turbulent jet is defined in relation to FIG. 1 as beingapproximately conical in form when produced by a circular jet formingorifice and having a virtual origin on its axis approximately fivediameters upstream of the plane of exit and the flow from the jetforming device and is clearly distinguished from what is known aslaminar flow, in which the streamlines are essentially parallel, asdescribed by Mott in US. Pat. No. 3,429,323, dated Feb. 25, 1969.

With the apparatus operating in the above manner, the pressure P givenby the manometer 4 will depend upon the density of the fluid substancesurrounding the apparatus and thus the density of this fluid substancemay be determined from this measurement.

One reason for the pressure P varying with the surrounding fluid densitymay be the variation of the spreading rate of the substantiallyunbounded turbulent jet with variations in the density of the fluid inwhich it is submerged. With a given momentum at the jet orifice, themomentum at the receiver mouth is primarily dependent on the spreadingrate of such turbulent jet. This phenomenon may be further complicatedby the effect of concentration of supply fluid and surrounding fluid atthe receiver mouth. These effects are also dependent on jet orifice toreceiver mouth spacing and to some extent on supply pressure.

Tests were carried out to determine the sensitivity of the apparatuswhen used to measure various gas densities by supplying the nozzle 1with air at various fixed pressures from the supply 3 and with variousspacings between the jet orifice 1 and the receiver mouth 2. In thesetests the manometer 4 was capable of giving a maximum reading of eightyinches of mercury.

The results of the tests are shown in the graphs of FIG. 2, where thehorizontal ordinate is the density of the surrounding gas in lbs/cu.ft., and the vertical ordinate is the pressure P in inches of Mercury.The air supply pressure from the air supply 3 for readings 5 was 15inches of mercury, for readings 6 was 30 inches of mercury, for readings7 was 45 inches of mercury, for readings 8 was 60 inches of mercury, andfor readings 9 was inches of mercury. The readings designated thus 0were for measuring the density of helium as a surrounding gas, and thus[:I for measuring the density of air as the surrounding gas and thus Afor measuring the density of monochlorodifluoromethane as thesurrounding gas.

The results of these tests indicate that, with the apparatus used, anair supply pressure of the order of 60 inches mercury from the airsupply 3 was the optimum value for a nozzle 1, to tube 2 spacing x offive diameters. The reason for this is that with an air supply pressureof the order of 60 inches of mercury the maximum change in pressure p"in the tube 2 is obtained for a given range of densities of gassurrounding the apparatus, and so the sensitivity of the apparatus isgreatest.

With the air supply pressure maintained at 60 inches of mercury thetests were continued using the same gases, but with the distance xbetween the nozzle 1 and the tube 2 set at different dimensions.

The results of these tests are shown in FIG. 3, where the pressure P isplotted against the density of the surrounding gas, in the same manneras in FIG. 2. In FIG. 3 the readings obtained were 10 with x" l0.35d, 11with x 7.15. d, 14 with x 6.08. d, 15 with x 5.00.d, and 16 with "x3.93. d". It will be noted that the readings 15 included 0 for argon, Afor carbon dioxide, and 1 for dichlorodifluoromethane.

From the results shown in FIG. 3, it can be seen that with the apparatusused a nozzle 1 to tube 2 spacing x of between eight of ten times d, thenozzle diameter, provides the maximum sensitivity at 60 inches ofmercury, air supply pressure. However, depending upon the apparatus usedthe spacing x may be up to 30 or even 50 times d and give usefulresults.

Using the apparatus as described a nozzle 1 to tube 2 spacing x of8.22.d, the sensitivity of the apparatus is approximately 50in/Hg/lb/cu. ft. at a gas density of the surrounding gas of 0.10lbs/cu.ft., 10 in .Hg/lb/cu.ft., at a gas density 0.50 lb/cu.ft, and 5in Hg/lb/cu. ft., at a gas density of l lb/cu.ft.

FIGS. 4 and 5 shows a similar apparatus to that shown in FIG. 1, andindentical parts shown therein are referred to by the same referencenumerals, and the previous description is relied upon to describe them.

In FIGS. 4 and 5 the apparatus shown in FIG. 1 is adapted for measuringthe density of a fluid substance when the apparatus is disposed within astream of the fluid substance. In order that the measurements of theapparatus will not be changed by the flow of the fluid v substance, andparticularlya flowtransverse to the tur- .bulentjet, the nozzle 1 andreceiver tube 2 are disposed within a cylindricalhousing l8 enclosingthe turbulent jet forming space, to allow substantially free interactionand mixing of the fluid surrounding such apparatus with the turbulentjet and not cause entrainment or attachment of the turbulent jet to thehousing. The cylindrical housing 18 is shown attached to the tube 2 by asupport 19. It will be appreciated that the cylindrical housing 18 couldbe similarly attached to the nozzle 1 and for rigidity could besimilarly attached to both noz-v zle l and the receiver tube 2 to form ameans of mounting and spacing said components.

In FIG. 6 where similar parts to those shown in FIGS. 4 and 5 arereferred to by the same reference nurnerals and the previous descriptionis relied upon to describe them, the cylindrical housing 18 is securedto the tube 2 by two supports 20 and 21 to secure the easing 18 to thetube 2 in a sturdy manner. The cylindrical casing 18 may be secured inthis manner to nozzle 1 in the same manner.

If desired any number of supports 20 and 21 may be used to secure thecasing 18 in position-provided they do not obstruct the mixing of thefluid surrounding such apparatus, including the casing 18, with theturbulent jet.

In FIG. 7 where 'similarparts to those shown in FIG. 1 are referred toby the same reference numeral, the nozzle 1 and tube 2 are disposedwithin a fluid-permeable casing in the form of a mesh'casing 21. Thecasing 21 is shown supported bya mesh 22a at one end.

If desired the casing 21 may be supported on the tube 2 by a furthermesh (not shown) at the other end of the casing 21. In other embodimentsthe casing 21' is supported in the nozzle 1 and/or tube 2 bythe-supports similar to those shown in FIG. 6. I

The casing 21 serves a similar purpose to the casing 18 in FIG. 4, butgreater access for fluid to the space between the nozzle 1 and the tube2. The casing 21, when closed at'one or both ends by mesh, alsoobstructs the passage of any particles, whose size approaches theinternal cross-sectional dimension of the tube 2, to the tube 2from thefluid whose density is being measured. In other words the casing 21obstructs the passage of particles to the tube 2 which would block thetube 2. The casing is particularly useful when the fluid whose densityis measured contains solid particles as will be described later.

In FIG. 8 there is shown a nozzle 2 and a receiver tube 23 both of whichfunction in a similar manner to the nozzle 1 and tube 2 shown in FIG. 1.The nozzle 22 and tube 23 are disposed between two inwardly curvedsupporting plates 24 and 25 which allow free interaction and mixing ofthe surrounding fluid with the jet on opposite sides of the jet. Theplates 24 and 25 extend beyond the nozzle 22 and tube 23, and are joinedto one another by the nozzle 22 and the tube 23. The curved plates 24and 25 provide better mechanical protection for the nozzle 22 and thetube 23 than plane plates, but in other embodiments one or both of theplates 24 and 25 may be plane, furthermore only one of the componentsselected from the group comprising the nozzle 22 or the tube 23 may bemounted between the plates 24 and 25. In different embodiments theplates 24 and 25 may be curved in a transverse direction to the jet fromthe nozzle 22 or one or both of the plates 24 and 25 may have a doublecurvature.

In FIG. 9 parts similar to those shown in FIG. 8 are designated bythesame reference numerals and the previous-description is relied uponto describe them. The nozzle 22 and tube 23 are disposed between twooutwardly curved plates 24a and 25a which allow free interaction andmixing of the surrounding fluid with the jet on opposite sides of thejet. The plates 24a and 25a extend beyond the nozzle 22 and receivertube 23 and are joined to one another by either or both the nozzle andtube 23. As in the embodiment described with reference to FIG. 8 thecurved plates 24a and 25a provide better mechanical protection for thenozzle 22 and .tube 23 than plane plates, but in other embodiments theone or both of the plates 24a and 250 may be curved in another axis orhave double curvature or may be plane, furthermore only one of thecomponents selected from the group comprising the nozzle 22 and tube 23may be mounted between the plates 24a and 25a.

In FIG. 10 parts similar to those shown in FIG. 8 are designated by thesame reference numerals and the previous description is relied upon'todescribe them. The nozzle and tube 23 are disposed between two plates24b and 25b which are curved in the same direction and which allow freeinteraction and mixing of the surrounding fluid with the jet on oppositesides of the jet. The plates 24b and 25b extend beyond the nozzle 22 andtube 23 and may be joined to one another by either or both the nozzle 22and tube 23. The curved plates 24b and 25b provide better mechanicalprotection for the nozzle 22 and tube 23 than plane plates. In

other embodiments the plates 24b and 2511 may be' curved transversely tothe jet and one or both of the plates may have double curvature or maybe plane. In other embodiments only one of the components selected fromthe group comprising the nozzle 22 and tube 23 is mounted between plates24b and 25b.

It will be appreciated that the nozzle and tube of any of the previousembodiments need not have passages or circular cross-section, however,the particular shape may affect the characteristics of the apparatus andthe manometer may have to be graduated in terms of the density of thegas to be measured to suit these characteristics.

In FIGS. 11 and 12 a nozzle and receiver tube 27 are shown mounted in acurved plate 28 which may (from a portion of a fluid passage (notshown))' be attached to or built into a surface bounding the fluid whosedensity is to be measured. With this apparatus the characteristics ofthe apparatus will also have to be taken into account but this apparatusillustrates how the invention may be incorporated into the duct or wallof a fluid containing member. The nozzle 26 and' tube 27 are shownhaving orifices of the nozzle 26 and tube 27 may also be disposed fromthe plate 28 and this may be desirable when the plate 28 (forms aportion of) is attached to or built into the wall of a fluid passagebecause these orifices may then be disposed in the passage at a positionbeyond the fluid bondary layer or area of reduced fluid velocity nearthe wall bounding the passage. The curved plate 28 may also be curved ina direction transverse to the jet or have a double curvature or be planeif desired.

In FIG. 13 there is shown a comparator which provides an output pressurewhich is proportional to the momentum in the contained jet. The momentumin the jet being a function of both density of the supply fluid and thedifference between the supply pressure to the jet orifice and thepressure of the fluid surrounding the comparator. The output of thecomparator is proportional to the output of any of the apparatusdescribed with reference to FIGS. 1 to 12 when such apparatus issurrounded by a fluid whose density is the same as the fluid supplied tothe nozzle of such apparatus and said comparator and the pressure of thefluid supplied to and surrounding such apparatus and such comparator isthe same.

The comparator shown in FIG. 13 comprises a second fluid jet formingdevice in the form of a nozzle 29 having a fluid jet orifice, a receivertube 30 forming a second receiver means and a casing 31 closed at oneend 32 and enclosing a turbulent jet forming space, this is a space thatallows the turbulent jet from the nozzle to expand in a manner similarto the expansion ofa turbulent jet in a volume which is substantiallyunbounded at least to one side and which is filled with the same fluidthat forms the jet. Such comparator casing also restricts anyinteraction between the jet enclosed by the jet enclosed by thecomparator casing 31 and 32 and the fluid surrounding such casing exceptfor the effect of the pressure of the surrounding fluid on the flow outof the comparator casing through any openings that are provided for suchflow out of the casing and excluding the openings which constitute thenozzle and receiver.

The turbulent jet forming space extending between the nozzle 29 and tube30 extends a distance of less than 50 times the maximum distance acrossthe orifice of the nozzle 29.

The geometry of the fluid jet orifice of the nozzle 29 is derived from aR is the Reynolds number and is in excess of 1700,

V is the velocity of the fluid delivered to the second device,

p is the density of the fluid delivered to the second device,

p. is the viscosity of the fluid delivered to the device,

and

It is the hydraulic radius obtained from, Ql h where A is the area ofthe fluid jet orifice, and

P is the distance around the perimeter of the fluid jet orifice of thesecond device.

By comparing the pressure in the tube 30 with the pressure in thereceiver tubes shown and described in embodiments illustrated in FIGS. 1to 13 variations in the pressure and density of the supply fluid and thepressure of the fluids surrounding both the comparator and the previousembodiments may be taken into account. The comparator may be disposed inthe same fluid substance as the fluid density measuring apparatus withwhich it is to be used as a reference. Alternately it may be disposed inanother fluid substance which may be isolated or in contact with thefluid substance whose density is to be measured.

A further function of the comparator is the provisions of a biaspressure, proportional to the difference between the supply pressure andthe pressure of the fluid surrounding such comparator, which is used topartially balance the output of any of the density measuring apparatus.described with reference to FIGS. 1 to 12. The partial balancing of theoutput from the density measuring apparatus, as described with referenceto FIGS. 1 to 12 against the output from the comparator reduces therange of differential pressure measurement required for the outputs ofsuch a combination of apparatus and thereby provides increasedsensitivity.

The comparator may take a number of forms such as that shown in FIG. 14where the tube 30 is mounted in an end wall 33 at the end of the casingopposite to the nozzle 29 and holes are provided in the casing 31 forfluid outlets.

The comparator shown in FIG. 15 has a nozzle 35 and a tube 36 mounted ina casing 37 provided with a fluid outlet 38.

In FIG. 16 there is shown a fluid supply 39, an apparatus for measuringa fluid density 40, a comparator 41, and a fluid pressure measuring,indicating, or recording device 42. The fluid supply 39 may be a pump,compressor, gas bottle or any other source of fluid under pressure, anda pressure regulator. Preferably a filter (not shown) is used to filterthe fluid from the supply 39. The apparatus 40 may be any one of thetypes described with reference to FIGS. 1 to 12 and the comparator 41may be any of the types described with reference to FIGS. 13 to 15. Thenozzles of the apparatus 40 and the comparator 41 are connected to thesupply 39. The tubes of the apparatus 40 and the comparator 41 areconnected to the device 42, which may be a pressure gauge, manometer,recorder, transducer, pressure transmitter, or any other device whichcan accept a fluid pressure and produce from it a useful output.

In operation the apparatus is arranged as shown in FIG. 16 with thedensity measuring apparatus of fluidic densitometer 40 and thecomparator or reference unit 41 disposed in the fluid whose density isto be measured. The fluid supply or power supply supplies fluid underequal pressure to the nozzles of the apparatus 40 and the comparator 41.The fluid pressures in the tubes of the apparatus 40 and the comparator41 are indicated or recorded by the device 42 from which the density ofthe fluid to be measured is deduced, if desired as a direct reading.

Where the pressure of the fluid, whose density is to be measured, islikely to change it may be desirable from the volume or the pressure ofthe fluid supply to the nozzles of the density measuring apparatus ofFIG. 16 to be adjusted accordingly.

In FIG. 17 there is shown an apparatus comprising a fluid supply 44,a-pressure ratio or pressure difference controller 46, a fluid densitymeasuring apparatus 47, a comparator 48, and a pressure measuring,indicating or recording device 49.

The apparatus is arranged as shown with the apparatus 47 and comparator48 disposed within a fluid 50 whose density is to be measured. Thisapparatus operates in the same manner as the apparatus shown in FIG. 14except that the controller maintains a constant difference or a constantabsolute pressure ratio between the pressure of the fluid supplied tothe nozzles of the apparatus 47 and the comparator 48 and the pressureof the fluid 50. Whether the controller maintains a constant differenceor a constant absolute pressure ratio will depend upon thecharacteristics required.

In FIG. 18 there is shown a nozzle 51 and tube 52. The nozzle 51 has athreaded exterior 53 with a portion 54 of the nozzle exterior recessedbeneath the thread and graduated. The nozzle 51 has a keyway 55 and isscrewed into a micrometer drum 56. The micrometer drum 56 is rotatablymounted in a support 57 and held therein by a collar 58 on the nozzle51. The support has a key 59 to slidably support the nozzle 51 butprevent rotation thereof. The rear end of the nozzle' 51 is connected bya flexible tube 60 to a source of pressurized fluid. The tube 52 is heldin a fixed position by a support 61.

it will be appreciated that the adjustment, as illustrated in FIG. 18,may beapplied to the receiver tube rather than the nozzle and furtherthat the nozzle or receiver tube may be allowed to rotate withadjustment provided a rotary joint is provided between the nozzle, orreceiver tube, 51 and the connecting tube 60.

In operation the nozzle 51 and tube function in the same manner as theprevious embodiments. This embodiment facilitates adjusting the distancex between the nozzle 51 and the tube 52 by rotating the micrometer drum56 to the desired setting. Thus the apparatus can be adjusted tocompensate for manufacturing inaccuracies in the nozzle or tube or forflow restrictions in the means for connecting the pressurized source tothe nozzle. Further the apparatus can be adjusted to suit any change inthe working conditions of the apparatus.

The use of the adjustment means, describedwith reference to FIG. 18,with any of the embodimentsdescribed with reference to FIGS. 1 to 12allows the sensitivity of such embodiments to be arranged to meetspecific requirements'by adjusting the nozzle orifice to receiverspacing as illustrated by the comparison of such spacing versussensitivity shown in FIG. 3.

The use of a comparator allows the adjustment 'with reference to FIG.18, to be used to adjust such apparatus tohave an output equal to thecomparator under specific conditions such as equal density and pressureof the surrounding fluid. Similarly a fixed geometry densitymeasuringapparatus can be balanced in output under specificconditions by the useof the adjustment described with reference to FIG. 18 applied to thecomparator.

The use of the adjustment, described with reference to H6. 18, with boththe density measuring apparatus and the comparator allows theadjustmentof both the sensitivity of the density measuring apparatus andthe corresponding bias output of the comparator under specificconditions.

It will be appreciated thatany of FIGS. 1 to 18 may be used to measurethe density of a stationary fluid or a fluid flowing in any directionrelative to the nozzle and tube.

This present invention need not involve pumping, compressing orcontrolling of the flow of fluid density is measured, nor does itinvolve the interaction of moving mechanical components with themeasured fluid. The present invention can therefore be used to measurethe density of high temperature, corrosive or explosive fluidsand-mixtures of fluids and solids. This requires only a fixed geometryand a knowledge of the supply pressure and supply fluid density toobtain an output pressure'which is a known function of surround ing ormeasured fluid density.

1 claim:

1. Apparatus for measuring the density of a fluid substance comprisinga. a fluid jet forming device having a fluid jet orifice,

pressure and cause a turbulent jet of fluid to issue from the orificeinto the fluid substance,

c. a receiver means including a receiver mouth facing the orifice to bepressurized by the dynamic pressure of the jet therefrom, and fluidsubstance entrained therein, within the area bounded by the receivermouth,

d. mounting means connecting the receiver means and the device with aturbulent jet forming space extending between them a distance of lessthan fifty times the maximum distance across the orifice,

e. means connected to said receiver means for measuring the fluidpressure therein, for providing an indication of the density of thefluid substance,

f. and wherein the geometry of the fluid jet orifice is derived from R(V hp)/u, where Y R is the Reynolds number and is in excess of 1700,

V is the velocity of the fluid delivered to the device, p is the densityof the fluid delivered to the device, p. is the viscosity of the fluiddelivered to the device,

and

h is the hydraulic radius obtained from, h=4 A/P A is the area of thefluid jet orifice, and

P, is the distance around the perimeter of the fluid jet 2. Apparatusaccording to claim I, further comprising a cylindrical casing which ispermeable to the fluid substance at both ends and encloses the turbulentjet forming space, and the mounting means mounts the device and thereceiver means coaxially within the casing.

3. Apparatus according to claim 2, wherein the easing is permeable tothe fluid substance, the mounting means includes an end closure atoneend of the casing, and the end closure is permeable to the fluidsubstance.

4. Apparatus for measuring the density of a fluid substance comprising,a first fluid jet forming device having a fluid jet orifice, apressurized fluid source connected to the firstdevice to deliver a fluidthereto at substantially constant pressure and cause a turbulent jet offluid to issue from the orifice into the fluid substance, a firstreceiver means including a receiver mouth, facing the first orifice, tobe pressurized by the dynamic pressure of the jet therefrom, and fluidsubstance entrained therein, within the area bounded by the receivermouth, mounting means connecting the first receiver means and the firstdevice with a turbulent jet forming space extending between them adistance of less than 50 times the maximum distance across the firstorifice the first fluid jet forming device and the first receiver meansare for disposition in a position of the fluid substance, and whichincludes a comparator comprising a second fluid jet forming devicehaving a fluid jet orifice, a pressurized fluid source connected to thesecond device to deliver a fluid thereto at substantially constantpressure and cause a second turbulent jet of fluid to issue from thesecond orifice into and entrain fluid having substantially the samedensity as the fluid substance, a second receiver means including areceiver mouth facing the orifice of the second device to be pressurizedby the dynamic pressure b. a pressurized fluid source connected to thedevice to deliver a fluid thereto at substantially constant of the jettherefrom, and fluid entrained therein, within the area bounded by thereceiver mouth, and a casing having an outlet for fluid from the secondjet and connecting the second receiver means and the second destance,and wherein the geometry of the first and secnd orifices is derived fromR is the Reynolds number and is in excess of 1700,

V is the velocity of the fluid delivered to the device whose orificegeometry is being derived,

p is the density of the fluid delivered to that device,

p. is the viscosity of the fluid delivered to that device,

h is the hydraulic radius obtained from, h (4A)/P where v AM-m '7 mwflmm-- A is the area of that fluid jet orifice, and

P, is the distance around the perimeter of that fluid jet orifice.

5. Apparatus according to claim '4, further comprising a pressurecontroller responsive to changes in the pressure of the fluid substancefor adjusting the supply pressure of fluid to the first and secondorifices in response to changes in the pressure of the fluid substance.

6. A method of measuring the density of a fluid substance comprising a.mounting a nozzle device and a receiver means in the fluid substancewith a receiver mouth of the receiver means facing an orifice of thedevice for the receiver mouth to be pressurized by the dynamic pressureof a jet therefrom and with a turbulent jet forming space extendingbetween the orifice and the receiver mouth ofless than fifty times themaximum distance across the orifice,

b. delivering a fluid at substantially constant pressure to the deviceto cause a turbulent jet to issue from the orifice into the fluidsubstance and pressurize the receiver means by means of the dynamicpressure in the turbulent jet and fluid substance entrained therein, and

c. measuring the fluid pressure within the receiver as a basis fordetermining the density of the fluid substance,

d. and wherein the geometry of the fluid jet orifice is derived from Ris the Reynolds number and is in excess of 1700,

V is the velocity of the fluid delivered to the device,

p is the density of the fluid delivered to the device,

u is the viscosity of the fluid delivered to the device,

and

is. t llr ulisrsd us ebtail simmrhimtll fi A is the area of the fluidjet orifice, and

P, is the distance around the perimeter of the fluid jet orifice of thedevice.

7. A method according to claim 6, comprising placing around theturbulent jet forming space, a cylindrical casing permeable at bothends, to substantially present changes in the fluid pressure within thereceiver by flow of the fluid substance.

8. A method of measuring the density of a fluid substance comprising,mounting a first nozzle device and a first receiver means in the fluidsubstance, with a receiver mouth of the first receiver means facing anorifice of the first device for the first receiver mouth to bepressurized by the dynamic pressure of a jet therefrom. and with aturbulent jet forming space extending between the first orifice and thefirst receiver mouth less than fifty times the maximum distance acrossthe first orifice, delivering a fluid at substantially constant pressureto the first device to cause a turbulent jet to issue from the orificeinto the fluid substance and pressurize the first receiver means bymeans of the dynamic pressure in the turbulent jet and fluid substanceentrained therein, mounting a comparator in fluid having substantiallythe same density as the fluid substance in which the first nozzle andfirst receiver are mounted, the comparator comprising a second nozzledevice and second receiver means, with a receiver mouth of the receivermeans facing the orifice of the second device to be pressurized by thedynamic pressure of a jet therefrom and fluid entrained therein, withthe area bounded by the receiver mouth, and a casing having an outletfor fluid from the second device and connecting the second receivermeans and the second device with a turbulent jet forming space extendingbetween them a distance of less than fifty times the maximum distanceacross the orifice of the second device, delivering a fluid atsubstantially constant pressure to the second device to cause a secondturbulent jet to issue from the orifice into and entrain the fluid andpressurize the receiver means by means of the dynamic pressure in thesecond turbulent jet and entrained fluid, and measuring the differentialfluid pressure between the pressures in the first and second receiversas a basis for determining the density of the fluid substance, andwherein the geometry of the orifices of the first and second devices arederived from

1. Apparatus for measuring the density of a fluid substance comprisinga. a fluid jet forming device having a fluid jet orifice, b. apressurized fluid source connected to the device to deliver a fluidthereto at substantially constant pressure and cause a turbulent jet offluid to issue from the orifice into the fluid substance, c. a receivermeans including a receiver mouth facing the orifice to be pressurized bythe dynamic pressure of the jet therefrom, and fluid substance entrainedtherein, within the area bounded by the receiver mouth, d. mountingmeans connecting the receiver means and the device with a turbulent jetforming space extending between them a distance of less than fifty timesthe maximum distance across the orifice, e. means connected to saidreceiver means for measuring the fluid pressure therein, for providingan indication of the density of the fluid substance, f. and wherein thegeometry of the fluid jet orifice is derived from R (V h Rho )/ Mu ,where R is the Reynolds number and is in excess of 1700, V is thevelocity of the fluid delivered to the device, Rho is the density of thefluid delivered to the device, Mu is the viscosity of the fluiddelivered to the device, and h is the hydraulic radius obtained from, h4 A/P1, where A is the area of the fluid jet orifice, and P1 is thedistance around the perimeter of the fluid jet orifice.
 2. Apparatusaccording to claim 1, further comprising a cylindrical casing which ispermeable to the fluid substance at both ends and encloses the turbulentjet forming space, and the mounting means mounts the device and thereceiver means coaxially within the casing.
 3. Apparatus according toclaim 2, wherein the casing is permeable to the fluid substance, themounting means includes an end closure at one end of the casing, and theend closure is permeable to the fluid substance.
 4. Apparatus formeasuring the density of a fluid substance comprising, a first fluid jetforming device having a fluid jet orifice, a pressurized fluid sourceconnected to the first device to deliver a fluid thereto atsubstantially constant pressure and cause a turbulent jet of fluid toissue from the orifice into the fluid substance, a first receiver meansincluding a receiver mouth, facing the first orifice, to be pressurizedby the dynamic pressure of the jet therefrom, and fluid substanceentrained therein, within the area bounded by the receiver mouth,mounting means connecting the first receiver means and the first devicewith a turbulent jet forming space extending between them a distance ofless than 50 times the maximum distance across the first orifice , thefirst fluid jet forming device and the first receiver means are fordisposition in a position of the fluid substance, and which includes acomparator comprising a second fluid jet forming device having a fluidjet orifice, a pressurized fluid source connected to the second deviceto deliver a fluid thereto at substantially constant pressure and causea second turbulent jet of fluid to issue from the second orifice intoand entrain fluid having substantially the same density as the fluidsubstance, a second receiver means including a receiver mouth facing theorifice of the second device to be pressurized by the dynamic pressureof the jet therefrom, and fluid entrained therein, within the areabounded by the receiver mouth, and a casing having an outlet for fluidfrom the second jet and connecting the second receiver means and thesecond device with a turbulent jet forming space extending between thema distance of less than fifty times the maximum distance across thesecond orifice, and means connected to the first and second receivermeans for measuring the differential pressure therebetween for providingan indication of the density of the fluid substance, and wherein thegeometry of the first and second orifices is derived from R (V h Rho )/Mu R is the Reynolds number and is in excess of 1700, V is the velocityof the fluid delivered to the device whose orifice geometry is beingderived, Rho is the density of the fluid delivered to that device, Mu isthe viscosity of the fluid delivered to that device, h is the hydraulicradius obtained from, h (4 A)/P1, where A is the area of that fluid jetorifice, and P1 is the distance around the perimeter of that fluid jetorifice.
 5. Apparatus according to claim 4, further comprising apressure controller responsive to changes in the pressure of the fluidsubstance for adjusting the supply pressure of fluid to the first andsecond orifices in response to changes in the pressure of the fluidsubstance.
 6. A method of measuring the density of a fluid substancecomprising a. mounting a nozzle device and a receiver means in the fluidsubstance with a receiver mouth of the receiver means facing an orificeof the device for the receiver mouth to be pressurized by the dynamicpressure of a jet therefrom and with a turbulent jet forming spaceextending between the orifice and the receiver mouth of less than fiftytimes the maximum distance across the orifice, b. delivering a fluid atsubstantially constant pressure to the device to cause a turbulent jetto issue from the orifice into the fluid substance and pressurize thereceiver means by means of the dynamic pressure in the turbulent jet andfluid substance entrained therein, and c. measuring the fluid pressurewithin the receiver as a basis for determining the density of the fluidsubstance, d. and wherein the geometry of the fluid jet orifice isderived from R (V h Rho )/ Mu R is the Reynolds number and is in excessof 1700, V is the velocity of the fluid delivered to the device, Rho isthe density of the fluid delivered to the device, Mu is the viscosity ofthe fluid delivered to the device, and h is the hydraulic radiusobtained from, h (4 A)/P1 A is the area of the fluid jet orifice, and P1is the distance around the perimeter of the fluid jet orifice of thedevice.
 7. A method according to claim 6, comprising placing around theturbulent jet forming space, a cylindrical casing permeable at bothends, to substantially present changes in the fluid pressure within thereceiver by flow of the fluid substance.
 8. A method of measuring thedensity of a fluid substance comprising, mounting a first nozzle deviceand a first receiver means in the fluid substance, with a receiver mouthof the first receiver means facing an orifice of the first device forthe first receiver mouth to be pressurized by the dynamic pressure of ajet therefrom, and with a turbulent jet forming space extending betweenthe first orifice and the first receiver mouth less than fifty times themaximum distance across the first orifice, delivering a fluid atsubstantially constant pressure to the first device to cause a turbulentjet to issue from the orifice into the fluid substance and pressurizethe first receiver means by means of the dynamic pressure in theturbulent jet and fluid substance entrained therein, mounting acomparator in fluid having substantially the same density as the fluidsubstance in which the first nozzle and first receiver are mounted, thecomparator comprising a second nozzle device and second receiver means,with a receiver mouth of the receiver means facing the orifice of thesecond device to be pressurized by the dynamic pressure of a jettherefrom and fluid entrained therein, with the area bounded by thereceiver mouth, and a casing having an outlet for fluid from the seconddevice and connecting the second receiver means and the second devicewith a turbulent jet forming space extending between them a distance ofless than fifty times the maximum distance across the orifice of thesecond device, deLivering a fluid at substantially constant pressure tothe second device to cause a second turbulent jet to issue from theorifice into and entrain the fluid and pressurize the receiver means bymeans of the dynamic pressure in the second turbulent jet and entrainedfluid, and measuring the differential fluid pressure between thepressures in the first and second receivers as a basis for determiningthe density of the fluid substance, and wherein the geometry of theorifices of the first and second devices are derived from R (V h)/ Mu Ris the Reynolds number and is in excess of 1700, V is the velocity ofthe fluid delivered to the device whose orifice geometry is beingderived, Rho is the density of the fluid delivered to that device, Mu isthe viscosity of the fluid delivered to that device, and h is thehydraulic radius obtained from, h (4A)/P1, where A is the area of thatfluid jet orifice, and P1 is the distance around the perimeter of thatfluid jet orifice.